1. Field of the Invention
The invention relates to an air-conditioning apparatus applied to a fuel cell vehicle, and a control method thereof.
2. Description of Related Art
In a conventional air-conditioning apparatus for a fuel cell vehicle that includes a fuel cell as a traveling drive source, a heating effect is improved by supplying heat from high-temperature cooling water used to cool the fuel cell, or in other words waste heat from the fuel cell, to a heater core for heating a cabin interior.
A conventional fuel cell vehicle air-conditioning apparatus of this type includes operating state detecting means for detecting or predicting a vehicle stoppage state, and thermal state detecting means for detecting at least one of a fuel cell temperature and an amount of stored heat in a fuel cell system, i.e., an amount of heat that can be used for heating. In the air-conditioning apparatus, when the vehicle stoppage state is detected or predicted during an operation, an amount of fuel cell waste heat collected in a heater core is varied in accordance with an output of the thermal state detecting means (see Japanese Patent Application Publication No. 2004-146144 (JP-2004-146144 A), for example).
According to the related art described in JP-2004-146144 A, the amount of waste heat used for heating is varied in accordance with the thermal state of the fuel cell system, and therefore excessive heat extraction from the fuel cell system can be avoided. As a result, the fuel cell can be maintained at a temperature enabling the fuel cell to operate efficiently, and the fuel cell can be reactivated quickly following a temporary stoppage so that power for the vehicle can be extracted. Hence, heating can be performed during an idling stop by means of a simple configuration.
In the related art described in JP-2004-146144 A, however, use of the waste heat stored in the fuel cell system for performing heating during a normal operation of a fuel cell vehicle is not envisaged.
Further, when surplus waste heat from the fuel cell is simply stored in the fuel cell system during a normal operation in the fuel cell vehicle, the temperature of the fuel cell rises beyond the temperature at which the fuel cell can operate efficiently. As a result, a power generation efficiency of the fuel cell may decrease, leading to deterioration of a fuel efficiency of the vehicle.